A magnetic resonance imaging (MRI) device, a magnetic resonance spectroscopy (MRS) device, and so forth are known as a magnetic resonance device exploiting the nuclear magnetic resonance (NMR) phenomenon.
The MRI device is used to obtain a sectional image of a subject (e.g., a human body) by using the NMR phenomenon. Owing to the NMR phenomenon, some atomic nuclei (e.g., hydrogen (1H), phosphorus (31P), sodium (23Na), carbon isotope (13C), and so forth) existing in a human body have their own rotating magnetic field constants. Accordingly, if an electromagnetic wave is applied to a magnetization vector of such an atomic nucleus, the magnetization vector may lie on a vertical plane owing to the resonance of the magnetization vector, and a magnetic resonance signal to be produced from the magnetization vector may be used to obtain an internal image of the human body. Here, an RF coil may be used to transmit an electromagnetic wave for inducing the resonance of the magnetization vector in the human body and to receive the magnetic resonance signal produced from the magnetization vector lying on the vertical plane owing to the resonance. Given that the RF coil is used to transmit an electromagnetic wave for the resonance of the magnetization vector and to receive the magnetic resonance signal, the RF coil may also be called an RF antenna. A single RF coil or antenna may be used not only to induce the resonance of the magnetization vector (in a transmission mode) but also to receive the magnetic resonance signal (in a reception mode), and in certain cases, two different RF coils may be used to separately perform the transmission mode and the reception mode. A single coil configured to perform in both the transmission and reception modes is called a transceiving coil, a coil for the transmission mode is called a transmission coil, and a coil for the reception mode is called a reception coil. Meanwhile, the RF coil may include a body type RF coil, which is provided in an exterior part of an MRI device, and a surface type RF coil or a volume type RF coil, which is attached to, or positioned adjacent to, a human body. Since the body type RF coil is provided in the exterior part of the MRI device, it may be formed on a cylinder-shaped frame or an elliptical cylinder-shaped frame that has a size allowing a human body to be entered therein and it may be used as the transceiving or transmission coil. By contrast, the surface or volume type RF coil may be attached to a human body and may be attachably/detachably provided to a table on which a human body lies. Generally, the surface or volume type RF coil may be produced to have a shape suitable for a part of a human body, and thus, it may include a head coil, a neck coil, a waist coil, and so forth. Furthermore, the surface or volume type RF coil may be used as the transceiving or reception coil.
The MRS device may be used to analyze physical, chemical, or biological properties of a material using the magnetic resonance phenomenon. In the MRS device, a transmission RF coil may be used to provide an RF signal into a subject, which is positioned within a magnetic field, thereby inducing a magnetic resonance phenomenon, and a reception RF coil may be positioned near the subject and may be used to detect a magnetic resonance signal. Since a difference in kinds of atoms in the subject leads to a difference in magnetic resonance frequency, by examining a spectrum of the magnetic resonance signal, it is possible to determine the kinds of atoms contained in the subject.
An RF surface coil, which is provided in the form of a loop coil or a loop coil array, is often used as the surface or volume type RF coil. Inductance of such an RF surface coil is determined by a shape of a coil. Accordingly, a conventional RF surface coil is controlled to have a capacitance value suitable for a magnetic resonance device in use and to be in accord with a center frequency of the magnetic resonance device.